U.S. patent number 7,804,511 [Application Number 11/896,098] was granted by the patent office on 2010-09-28 for image forming apparatus, exposure apparatus, image holder, image forming method, and exposing method.
This patent grant is currently assigned to Fuji Xerox Co., Ltd.. Invention is credited to Satoshi Honobe, Yukihiro Ichiki, Tomokazu Kurita, Toshiyuki Matsui, Taro Mitsui, Junichi Ozawa, Shigeru Tanaka.
United States Patent |
7,804,511 |
Honobe , et al. |
September 28, 2010 |
Image forming apparatus, exposure apparatus, image holder, image
forming method, and exposing method
Abstract
An image forming apparatus includes: an image holder; an
exposure member that has an exposure portion exposing the image
holder; a first positioning unit that determines a distance in a
first direction, which is a direction of an optical axis of the
exposure member, between the exposure member and the image holder;
and a second positioning unit that determines a position of the
exposure member with respect to the image holder in a second
direction being a direction of an axis line of the image holder,
and a position of the exposure member with respect to the image
holder in a third direction being perpendicular to both the first
direction and the second direction, and that determines the
distance between the exposure member and the image holder at a
position substantially closer to the exposure member than the
position of the first positioning unit.
Inventors: |
Honobe; Satoshi (Kanagawa,
JP), Kurita; Tomokazu (Kanagawa, JP),
Tanaka; Shigeru (Kanagawa, JP), Ozawa; Junichi
(Kanagawa, JP), Mitsui; Taro (Kanagawa,
JP), Ichiki; Yukihiro (Kanagawa, JP),
Matsui; Toshiyuki (Kanagawa, JP) |
Assignee: |
Fuji Xerox Co., Ltd. (Tokyo,
JP)
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Family
ID: |
39527406 |
Appl.
No.: |
11/896,098 |
Filed: |
August 29, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080145103 A1 |
Jun 19, 2008 |
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Foreign Application Priority Data
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Dec 8, 2006 [JP] |
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P2006-332368 |
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Current U.S.
Class: |
347/149; 347/238;
347/130; 347/152; 347/118; 347/138; 347/117; 347/245; 347/263 |
Current CPC
Class: |
G03G
15/04054 (20130101); G03G 2215/0409 (20130101) |
Current International
Class: |
B41J
2/385 (20060101); B41J 2/435 (20060101); B41J
2/45 (20060101); B41J 2/00 (20060101); B41J
2/41 (20060101) |
Field of
Search: |
;347/238,242,245,263 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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7-195734 |
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Aug 1995 |
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JP |
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07195734 |
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Aug 1995 |
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JP |
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2005-115236 |
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Apr 2005 |
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JP |
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2006-84637 |
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Mar 2006 |
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JP |
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Primary Examiner: Luu; Matthew
Assistant Examiner: Liu; Kendrick X
Attorney, Agent or Firm: Morgan, Lewis & Bockius LLP
Claims
What is claimed is:
1. An image forming apparatus comprising: an image holder; an
exposure member that has an exposure portion exposing the image
holder; a first positioning unit that determines a distance in a
first direction, which is a direction of an optical axis of the
exposure member, between the exposure member and the image holder;
and a second positioning unit that determines a position of the
exposure member with respect to the image holder in a second
direction being a direction of an axis line of the image holder,
and a position of the exposure member with respect to the image
holder in a third direction, the third direction being
perpendicular to both the first direction and the second direction,
wherein the first positioning unit is disposed closer to the
exposure member than the second positioning unit at a same side of
the exposure member, wherein the first positioning unit is disposed
closer with respect to the second direction to the exposure member
than the second positioning unit as a same side of the exposure
member with respect to the second direction.
2. The image forming apparatus as claimed in claim 1, wherein the
first positioning unit comprises: a first projection portion that
is provided at a side of the exposure member to project from the
exposure member to the image holder; and a first support portion
that supports the first projection portion at a side of the image
holder, and the second positioning unit comprises: a second
projection portion that is provided at a position, which is farther
from the exposure member in the second direction than the first
projection portion, at a side of the exposure member to project
from the exposure member to the image holder; and a second support
portion that supports the second projection portion at a side of
the image holder.
3. The image forming apparatus as claimed in claim 1, further
comprising a first pushing member that pushes the exposure member
in the second direction, wherein the first positioning unit
comprises: a first projection portion that is provided at a side of
the exposure member to project from the exposure member to the
image holder; and a first support portion that supports the first
projection portion at a side of the image holder, and the second
positioning unit comprises: a third projection portion that is
provided at a position, which is farther from the exposure portion
in the second direction than the first projection portion, at a
side of the exposure member to project from the exposure member to
the image holder; and a third support portion that supports the
third projection portion at a side of the image holder, and that
have two surfaces determining a position of the third projection
portion in the second direction and a position of the third
projection portion in the third direction by causing the first
pushing member to push the exposure member in the second direction,
wherein the two surfaces of the third support member are configured
so that a distance in the third direction between the two surfaces
continuously decreases toward a pushing direction of the first
pushing member, define an opening portion at which the distance in
the third direction between the two surfaces has a maximum value,
and are configured to be larger than a width of the third
projection portion in the third direction.
4. The image forming apparatus as claimed in claim 3, wherein the
exposure member is contactable with and separatable from the image
holder in the first direction, and a movement limiting unit limits
movement in the second direction of the exposure member so that an
end part of the third projection portion is placed in a region,
onto which the third support portion is projected from the first
direction, in a state where the exposure member is moved far from
the image holder.
5. The image forming apparatus as claimed in claim 3, wherein the
exposure member is movable with respect to the image holder in the
first direction, and a movement limiting unit limits movement in
the second direction of the exposure member so that an end part of
the third projection portion is placed in the second support
portion in a state where the exposure member is moved far from the
image holder.
6. The image forming apparatus as claimed in claim 5, further
comprising an image holding replacement unit that includes the
image holder, and that is attached to and detached from the image
forming apparatus by being moved in the second direction to the
image forming apparatus integrally with the image holder, wherein
the third support portion is provided at a side of a body of the
image forming apparatus.
7. The image forming apparatus as claimed in claim 1, further
comprising a third positioning unit on an opposite side of the
image holder from the first positioning unit such that the first
and third positioning units define a first pair of positioning
units that determine the distance in the first direction between
the exposure member and the image holder.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based on and claims priority under 35 U.S.C.
119 from Japanese Patent Application No. 2006-332368 filed Dec. 8,
2006.
BACKGROUND
1. Technical Field
The present invention relates to an image forming apparatus, an
exposure apparatus, an image holder, an image forming method, and
an exposing method.
2. Related Art
An apparatus employing light emitting element array, in which light
emitting elements, such as LEDs, are disposed in a line, has been
proposed as an exposure apparatus that exposes an image on an image
holder, such as a photoreceptor drum, in an image forming
apparatus, such as a printer and a copier, employing an
electrophotographic method.
SUMMARY
According to an aspect of the present invention, an image forming
apparatus includes: an image holder; an exposure member that has an
exposure portion exposing the image holder; a first positioning
unit that determines a distance in a first direction, which is a
direction of an optical axis of the exposure member, between the
exposure member and the image holder; and a second positioning unit
that determines a position of the exposure member with respect to
the image holder in a second direction being a direction of an axis
line of the image holder, and a position of the exposure member
with respect to the image holder in a third direction being
perpendicular to both the first direction and the second direction,
and that determines the distance between the exposure member and
the image holder at a position substantially closer to the exposure
member than the position of the first positioning unit.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiment of the present invention will be described in
detail based on the following figures, wherein:
FIG. 1 is a view illustrating an example of the entire
configuration of an image forming apparatus to which the invention
is applied;
FIG. 2 is a view illustrating the configuration of an LED print
head (LPH);
FIG. 3 is a plan view illustrating an LED circuit board;
FIG. 4 is a view illustrating an LED;
FIG. 5 is a view illustrating an LPH positioning mechanism;
FIG. 6 is a plan view illustrating positions at which first
projection members and second projection members are respectively
disposed;
FIG. 7 is a view illustrating the positional relation among and the
cross-sectional shapes of a photoreceptor drum, first projection
members, Y-direction support members, second projection members,
and XZ-direction support members in a state in which the LPH is set
at an exposure position;
FIG. 8 is a cross-sectional view illustrating a region of a
front-side end portion of the photoreceptor drum;
FIG. 9 is a view illustrating a state in which a retracting member
is slide-moved from a front side to a rear side;
FIG. 10 is a view illustrating the relative positions of an end
portion of the second projection member 252F and the XZ-direction
support member 123F;
FIGS. 11A, 11B, and 11C are views illustrating the relative
positional positions of the first projection member and the
XZ-direction support member when the LPH is moved from a position,
at which the LPH is detached from a photoreceptor module and is set
at an exposure position;
FIG. 12 is a cross-sectional view illustrating a state in which the
first projection member is supported by the XZ-direction support
member; and
FIG. 13A is a cross-sectional view taken on line L-L shown in FIG.
5. FIG. 13B is a cross-sectional view taken on line N-N shown in
FIG. 5.
DETAILED DESCRIPTION
Hereinafter, an embodiment of the invention is described in detail
with reference to the accompanying drawings.
FIG. 1 illustrates an example of the entire configuration of an
image forming apparatus 1 to which the present embodiment of the
invention is applied. The image forming apparatus 1 illustrated in
FIG. 1 is a digital color printer of what is called the tandem
type. The image forming apparatus 1 includes an image formation
processing portion 10 configured to perform image formation
corresponding to image data of each color, a controller 30
configured to control an operation of the entire image forming
apparatus 1, an image processing portion 35 which is connected to
external apparatuses, for example, a personal computer (PC) 3 and
an image reading apparatus 4 and which performs predetermined image
processing on image data received from the external apparatuses,
and a main power supply 70 configured to supply electric power to
each of the portions.
The image formation processing portion 10 has four image forming
units 11Y, 11M, 11C, and 11K disposed in parallel at predetermined
intervals (hereunder referred to generically and simply as "image
forming units 11"). Each of the image forming units 11 includes a
photoreceptor drum 12 serving as an image holder that generates an
electrostatic latent image and holds a toner image, an
electrification unit 13 that uniformly electrifies a surface of the
photoreceptor drum 12 at a predetermined electric potential level,
an LED print head (LPH) 14 that is an example of an exposure
apparatus (or exposure member) that exposes the photoreceptor drum
12 electrified by the electrification unit 13 according to image
data, a developing unit 15 that develops the electrostatic latent
image formed on the photoreceptor drum 12, and a cleaner 16 that
cleans the surface of the photoreceptor drum 12 after the transfer
of a toner image.
Each of the image forming units 11 is substantially similarly
constituted except for toner accommodated in the developing unit
15. The image forming units 11 form an yellow (Y) toner image, a
magenta (M) toner image, a cyan.COPYRGT. toner image, and a black
(K) toner image, respectively.
Additionally, the image formation processing portion 10 has an
intermediate transfer belt 20 onto which toner images formed by the
photoreceptor drums 12 of the image forming units 11 are
multiply-transferred, a primary transfer roll 21 that sequentially
transfers (or primarily transfers) toner images respectively formed
by the image forming units 11 onto the intermediate transfer belt
20, a secondary transfer roll 22 that collectively transfers (or
secondarily transfers) toner images, which are superposed on the
intermediate transfer belt 20, to paper P serving as a recording
material (or recording paper), and a fixing unit 50 that fixes the
secondary-transferred image onto the paper P.
Incidentally, in each of the image forming units 11, the
photoreceptor drum 12, the electrification unit 13, and the cleaner
16 are integrally configured as a module (hereunder referred to as
a "photoreceptor module MOD") serving as an image holder unit.
Additionally, the photoreceptor module MOD is configured attachably
to and detachably from the image forming apparatus 1. The
photoreceptor module MOD can be replaced with another according to
the lifetime of the photoreceptor drum 12. Incidentally, the
photoreceptor module MOD can employ a configuration formed by
including only the photoreceptor drums 12, or a configuration
formed to be integral with the above composing elements and the
developing units 15. That is, as long as the photoreceptor module
MOD includes the photoreceptor drums 12 each of which has a
lifetime shorter than those of the other composing elements, the
photoreceptor module MOD can be constituted by a combination of any
composing elements. However, the present embodiment assumes that
the photoreceptor module MOD is formed separately from the LPH
14.
Additionally, the LPH 14 is configured by an approaching/separating
mechanism (i.e., a retracting mechanism), which will be described
later, to be contactable with and sepratable from the photoreceptor
drum 12 between a predetermined position (i.e., an exposure
position) at each exposure of the photoreceptor drum 12, which is
set when an image is formed, and a position separated from the
photoreceptor drum 12, which is set, for example, at the
attachment/detachment of the photoreceptor module MOD.
In the image forming apparatus 1 according to the present
embodiment, the image formation processing portion 10 performs an
image forming operation according to various controls signals
supplied from the controller 30. That is, the image processing
portion 35 performs image processing on image data input from the
PC 3 and the image reading apparatus 4 under the control of the
controller 30. The processed image data is supplied to each of the
image forming units 11 through an interface (not shown). Then, for
example, in the image forming unit 11K corresponding to black (K),
the photoreceptor drum 12 is uniformly electrified at a
predetermined potential level by the electrification unit 13 while
rotating in the direction of arrow A. The LPH 14 adapted to emit
light according to the image data transmitted from the image
processing portion 35 exposes the photoreceptor drum 12.
Consequently, an electrostatic latent image corresponding to a
black (K) image is formed on the photoreceptor drum 12. Then, the
electrostatic latent image formed on the photoreceptor drum 12 is
developed by the developing unit 15. Thus, a black (K) toner image
is formed on the photoreceptor drum 12. Similarly, a yellow (Y)
toner image, a magenta (M) toner image, and a cyan (C) toner image
are formed in the image forming units 11Y, 11M, and 11C,
respectively.
The color toner images formed in the image forming units 11 are
sequentially and electrostatically attracted on the intermediate
transfer belt 20, which moves in the direction of arrow B, by the
primary rolls 21 to thereby form a synthetic toner image on which
the color toner images are superposed. The synthetic toner image
formed on the intermediate transfer belt 20 is conveyed to a region
(i.e., a secondary transfer portion T2) as the intermediate
transfer belt 20 moves. Paper P is supplied to the secondary
transfer portion T2 from a paper holding portion 40 in
synchronization with timing with which the toner image is conveyed
to the secondary transfer portion T2. Then, the synthetic toner
images are collectively and electrostatically transferred by a
transfer electric field generated by the secondary transfer rolls
22 in the secondary transfer portion T2 onto the conveyed paper
P.
Subsequently, the paper P onto which the synthetic toner image is
electrostatically transferred, is peeled off the intermediate
transfer belt 20 and is conveyed to the fixing unit 50 through a
conveyance guide 23. The synthetic toner image on the paper P
conveyed to the fixing unit 50 is fixed by the fixing unit 50 by
undergoing a fixing process using heat and pressure. Then, the
paper P, on which the fixed image is formed, is conveyed to a paper
loading portion 45 provided in a discharge portion of the image
forming apparatus 1.
On the other hand, upon completion of the secondary transfer, toner
(i.e., transfer residual toner) adhering to the intermediate
transfer belt 20 is removed for the next image formation cycle by a
belt cleaner 25 from the surface of the intermediate transfer belt
20.
Thus, the image forming apparatus 1 iteratively performs image
formation a plurality of times the number of which is equal to that
of printed images.
FIG. 2 is a cross-sectional view illustrating the configuration of
the LED print head (LPH) 14 serving as the exposure apparatus. As
shown in FIG. 2, the LPH 14 has a housing 61 serving as a support
body, an LED array (LED) 63 serving as an example of a light
source, an LED circuit board on which the LED 63 and a signal
generating circuit 100 adapted to generate drive signals according
to which the LED 63 is driven, a rod lens array 64 serving as an
example of an optical member forming an image on a surface of the
photoreceptor drum 12 from light emitted by the LED 63, a holder 65
configured to support the rod lens array 64 and to shield the LED
63 from the outside, and a plate spring 66 configured to press the
housing 61 in the direction of the rod lens array 64.
The housing 61 is formed of a metal block made of aluminum or SUS
or formed of a sheet metal and supports the LED circuit board 62.
The holder 65 supports the housing 61 and the rod lens array 64 and
sets the luminous point of the LED 63 to coincide with a focal
plane of the rod lens array 64. The holder 65 is configured to seal
the LED 63. Consequently, dust is prevented from externally
adhering to the LED 63. On the other hand, the plate spring 66
presses the LED circuit board 62 through the housing 61 in the
direction of the rod lens array 64 to hold the positional relation
between the LED 63 and the rod lens array 64.
The LPH 14 constituted in this manner is configured to be able to
move in the direction of the optical axis of the rod lens array 64
by an adjustment screw. The LPH 14 is adjusted so that an imaging
location (i.e., a focal plane) is positioned on the photoreceptor
drum 12.
As illustrated in FIG. 3 which is a plan view of the LED circuit
board 62, the LED 63 including, for example, 58 LED chips CHIP1 to
CHIP58 is disposed in a line with good accuracy, which is parallel
to an axial direction of the photoreceptor drum 12. In this case,
the LED chips CHIP1 to CHIP58 are disposed in a zigzag alignment to
be continuous at end boundary portions of arrays (i.e., LED arrays)
of light emitting devices (LED) disposed on each of the LED chips
CHIP1 to CHIP58.
Also, a signal generating circuit 100 configured to generate
signals (i.e., drive signals) to the LED 63, a level shift circuit
108, a 3-terminal regulator 101 adapted to output a predetermined
voltage, an EEPROM 102 adapted to store light-amount-correction
data of the LED 63, and a harness 103 that is supplied with
electric power from the main power supply 70 and that is used for
the transmission/reception of signals between the controller 30 and
the image processing portion 35 are mounted on the LED circuit
board 62.
FIG. 4 illustrates the LED 63. The LED 63 according to the present
embodiment is supplied with various drive signals from the signal
generating circuit 100 and the level shift circuit 108. That is,
the signal generating circuit 100 generates transfer signals CK1R,
CK1C, CK2R and CK2C, according to which the LEDs arranged in the
LED array 63 are sequentially put into a lightable state, and
lighting signals .phi.I according to which the LEDs are
sequentially turned on in accordance with image data sent from the
image processing portion 35. Additionally, the signal generating
circuit 100 outputs the transfer signals CK1R, CK1C, CK2R and CK2C
to the level shift circuit 108 and also outputs the lighting
signals .phi.I to the LED array 63.
The level shift circuit 108 has a configuration in which a resistor
R1B and a capacitor C1 are disposed in parallel to each other, and
in which a resistor R2B and a capacitor C2 are disposed in parallel
to each other. One end of each of the resistor R1B, the capacitor
C1, the resistor R2B, and the capacitor C2, is connected to an
input terminal of the LED array 63. The other end of each of the
resistor R1B, the capacitor C1, the resistor R2B, and the capacitor
C2, is connected to an output terminal of the LED array 63. The
level shift circuit 108 generates the transfer signal CK1 according
to the transfer signals CK1R and CK1 output from the signal
generating circuit 100 and outputs the generated transfer signal
CK1. Also, the level shift circuit 108 generates the transfer
signal CK1 according to the transfer signals CK1R and CK1C output
from the signal generating circuit 100 and outputs the generated
transfer signal CK1 to the LED array 63. Additionally, the level
shift circuit 108 generates the transfer signal CK2 according to
the transfer signals CK2R and CK2C output from the signal
generating circuit 100 and outputs the generated transfer signal
CK2 to the LED array 63.
On the other hand, the LED array 63 according to the present
embodiment includes, for example, 128 thyristors S1 to S128 serving
as switching devices, 128 LEDs L1 to L128 serving light emitting
devices, 128 diodes D1 to D128, 128 resistors R1 to R128, and
current limiting resistors R1A and R2A adapted to prevent excessive
currents from flowing through signal lines .phi.1 and .phi.2,
respectively, as main composing elements thereof.
The anode terminals (i.e., the input terminals) A1 to A128 of the
thyristors S1 to S128 are connected to a power supply line 55. The
thyristors S1 to S128 are supplied with a drive voltage VDD
(VDD=+3.3V) from the 3-terminal regulator 101 (see FIG. 3) through
the power supply line 55.
On the other hand, the gate terminals (i.e., the control terminals)
G1 to G128 of the thyristors S1 to S128 are connected to a power
supply line 56 through resistors R1 to R128 respectively provided
corresponding to the thyristors S1 to S128. Thus, the thyristors S1
to S128 are grounded (GND) through the power supply line 56.
Transfer signals CK1 from the signal generating circuit 100 and the
level shift circuit 108 are sent through the transfer current
limiting resistor R1A to the cathode terminals (i.e., the output
terminal) K1, K3, . . . , K127 of the odd-numbered thyristors S1,
S3, . . . , S127, respectively. Also, transfer signals CK2 from the
signal generating circuit 100 and the level shift circuit 108 are
sent through the transfer current limiting resistor R2A to the
cathode terminals (i.e., the output terminal) K2, K4, . . . , K128
of the odd-numbered thyristors S2, S4, . . . , S128,
respectively.
Additionally, the cathode terminals of the LEDs L1 to L128 are
connected to the signal generating circuit 100. Thus, the lighting
signals .phi.I are sent to the LEDs L1 to L128.
The signal generating circuit 100 according to the present
embodiment sets the signal level of each of the transfer signals
CK1R and CK1C and the transfer signals CK2R and CK2C to change from
a high level (hereunder described as "H") to a low level (hereunder
described as "L") with predetermined timing, and then change from
"L" to "H" with predetermined timing. Consequently, the potential
level of the transfer signal CK1 output from the level shift
circuit 108 is set to repeatedly change from "H" to "L" and then
from "L" to "H". Also, the potential level of the transfer signal
CK2 output from the level shift circuit 108 alternately with the
transfer signal CK1 is set to repeatedly change from "H" to "L" and
then from "L" to "H". Thus, for example, in each of the LED chips,
the odd-numbered thyristors S1, S3, . . . , S127 are sequentially
caused in this order to perform a transfer operation of turning
off, turning on, and turning off, . . . . Similarly, the
even-numbered thyristors S2, S4, . . . , S128 are sequentially
caused in this order to perform a transfer operation of turning
off, turning on, and turning off, . . . . Consequently, the
thyristors S1 to S128 are serially caused in the order of S1, S2, .
. . , S127, and S128 to perform a transfer operation of turning
off, turning on, and turning off, . . . . Also, the lighting signal
.phi.I is output in synchronization with the transfer operation.
Consequently, the LEDs L1 to L128 are sequentially turned on in the
order of L1, L2, . . . , L127, and L128.
Thus, in the LPH 14 according to the present embodiment, the LEDs
L1 to L128 of each of all the LED chips HIP1 to CHIP58 provided on
the LED circuit board 62 are turned on in the order of L1, L2, . .
. , L127, and L128. Thus, a scanning exposure is performed on the
photoreceptor drum 12 according to image data.
In this case, it is necessary that the exposure from the LPH 14 is
performed in parallel to the axis line of the photoreceptor drum 12
to prevent skew and distortion from occurring in a formed image.
Thus, when the LPH 14 is provided in the image forming apparatus 1,
it is requested to highly accurately perform the positioning of the
exposure portion with respect to the axis line of the photoreceptor
drum 12. In a case where the image holder has a cylindrical shape
like the photoreceptor drum 12 according to the present embodiment,
the axis line of the photoreceptor drum 12 (corresponding to the
image holder) is the centerline of the rotating shaft 121 (see FIG.
5 which will be described later) of the photoreceptor drum 12.
Also, for example, in a case where the photoreceptor (a belt
photoreceptor) has a belt-shaped image holder and where exposures
is performed on a planar portion of the belt photoreceptor, a line
which is perpendicular to a direction of movement of a surface of
the belt photoreceptor and is directed in a direction parallel to a
surface of the belt photoreceptor in an exposure region is the axis
line of the photoreceptor drum 12.
Next, the positioning mechanism for the LPH 14 in the image forming
apparatus 1 according to the present embodiment is described
below.
FIG. 5 is a view illustrating the positioning mechanism for the LPH
14 according to the present embodiment. A left-side part of FIG. 5
is a front side of the image forming apparatus 1, at this side of
which a detachment/detachment operation is performed on the
photoreceptor module MOD. A right-side part of FIG. 5 is a rear
side of the image forming apparatus 1, at this side of which a
driving force of a drive motor adapted to rotationally drive the
photoreceptor drum 12 is transmitted thereto. Incidentally, in the
present specification, character "F" is suffixed to a number
designating a member disposed at the front side of the image
forming apparatus 1. Character "R" is suffixed to a number
designating a member disposed at the rear side of the image forming
apparatus 1.
As illustrated in FIG. 5, in the housing 61 of the LPH 14 according
to the present embodiment, the first projection members 251F and
251R serving examples of the first projection portion configured to
determine the position in the direction of the optical axis (i.e.,
the first direction which is defined to be a "Y-direction") of the
rod lens array 64 of the LPH 14 are disposed. Also, the second
projection members 252F and 252R serving examples of the second
projection portion and the third projection portion configured to
simultaneously determine the position in the direction of the axis
line (i.e., the second direction which is defined to be the
"Z-direction") and the position in the direction (i.e., the third
direction which is defined to be an "X-direction") perpendicular to
both the Y-direction and the Z-direction are disposed.
On the other hand, in the photoreceptor module MOD supporting the
photoreceptor drum 12 according to the present embodiment, the
Y-direction support members 122F and 122R serving as examples of
the first support portion configured to set the Y-direction
position of the LPH 14 by causing the first projection members 251F
and 251R provided at the side of the LPH 14 to abut against the
Y-direction support members 122F and 122R, respectively, are
disposed coaxially with the rotating shaft 121 of the photoreceptor
drum 12. Also, the XZ-direction support members 123F and 123R
serving as examples of the second and third support portions
configured to simultaneously set the X-direction position and the
Z-direction position of the LPH 14 by supporting the second
projection members 252F and 252R at the side of the LPH 14 serving
as examples of the second and third projection portions are
disposed.
Further, in the image forming apparatus 1 according to the present
embodiment, the first projection member 251F and the Y-direction
support member 122F constitute the first positioning means
configured to set the Y-direction position of the LPH 14.
Similarly, the first projection member 251R and the Y-direction
support member 122R constitute the first positioning means.
Also, the second projection member 252F and the XZ-direction
support member 123F constitute the second positioning means
configured to simultaneously set the X-direction position and the
Z-direction position of the LPH 14. Similarly, the second
projection member 252R and the XZ-direction support member 123R
constitute the second positioning means.
Next, FIG. 6 is a plan view illustrating the placement positions of
the first projection members 251F and 251R and the second
projection members 252F and 252R of the LPH 14 of the present
embodiment. In the LPH 14, each of the first projection members
251F and 251R and the second projection members 252F and 252R is
constituted by a cylindrical member having a predetermined outside
diameter. The first projection members 251F and 251R and the second
projection members 252F and 252R are provided to protrude
perpendicularly to a surface of the housing 61, which faces the
photoreceptor drum 12. The first projection members 251F and 251R
and the second projection members 252F and 252R are disposed so
that the center axis of each of the first projection members 251F
and 251R and the second projection members 252F and 252R coincides
with the array line of the rod lens array 64 arranged in a
direction that coincides with a direction in which the LED chips
CHIP1 to CHIP58 are arranged.
The first projection members 251F and 251R are disposed closer to
the rod lens array 64 than the second projection members 252F and
252R. Thus, when the Y-direction support members 122F and 122R
provided at the photoreceptor module MOD abut against the first
projection members 251F and 251R (see also FIG. 5), the first
projection members 251F and 251R serve as supporting points to
prevent the rod lens array 64 from being bowed by the pushing force
of the lifting spring 211. Incidentally, it is preferable from such
a viewpoint that each of the lifting springs 211 is disposed in the
vicinity of the position, at which an associated one of the first
projection members 251F and 251R is disposed, or at a place closer
to the rod lens array 64 than this position.
When the image forming apparatus 1 performs an image forming
operation, the LPH 14 is set at the predetermined exposure
position, at which the exposure is performed on the photoreceptor
drum 12, by an approaching/separating mechanism (i.e., a retracting
mechanism), which will be described in detail later. FIG. 5
illustrates a state in which the LPH 14 is set at this exposure
position. In the image forming apparatus 1 according to the present
embodiment, in a state in which the LPH 14 is set at the exposure
position, the first projection members 251F and 251R are configured
to abut against the Y-direction support members 122F and 122R,
respectively. Thus, the Y-direction position of the LPH 14 is set.
Also, the second projection members 252F and 252R at the side of
the LPH 14 are configured to support the XZ-direction support
members 123F and 123R. Consequently, the X-direction position and
the Z-direction position of the LPH 14 are simultaneously set.
FIG. 7 is a view illustrating the positional relation among and the
cross-sectional shapes of the photoreceptor drum 12, the first
projection members 251F and 251R, the Y-direction support members
252F and 252R, the second projection members 252F and 252R, and the
XZ-direction support members 123F and 123R in a state in which the
LPH is set at an exposure position.
As shown in FIG. 7, a cross-sectionally V-shaped groove portion
123Fh having a substantially V-cross-sectional shape, which is
formed symmetrically in the X-direction with respect to the axis
line of the photoreceptor drum 12 so that a vertex is set on the
axis line of the photoreceptor drum 12 in an X-plane, is formed in
the XZ-direction support member 123F. This groove portion 123Fh
supports the second projection member 252F, so that the center of
the second projection member 252F is set on the axis line of the
photoreceptor drum 12. That is, the LPH 14 is pushed in a direction
(the Z-direction) from a rear surface side to the side of the
XZ-direction by the press spring 212 serving as an example of the
first pushing member provided in a body frame FRA. Thus, the second
projection member 252F is pushed toward the XZ-direction support
member 123F in the groove portion 123Fh of the XZ-direction support
member 123F. Consequently, the second projection member 252F
supports a V-shaped portion side surface of the groove portion
123Fh at two points. Thus, the center position of the second
projection member 252F in the X-plane is set to coincide with the
axis line position of the photoreceptor drum 12.
Incidentally, "the substantially V-cross-sectional shape of the
groove portion 123 Fh" is a shape configured so that the distance
between the two surfaces of the groove portion 123Fh in the X-plane
is continuously reduced in a direction in which the press spring
212 is pushed.
A cross-sectionally substantially rectangular-shaped groove portion
123Rh having a substantially rectangle cross-sectional shape, whose
both end portions are constituted by curves is formed in the
XZ-direction support member 123R. The groove portion 123Rh is
formed to have a width in the X-direction substantially equal to
the outside diameter (i.e., a length obtained by adding a
manufacturing tolerance to such an outside diameter) of the second
projection member 252R. Further, the groove portion 123Rh is formed
to be symmetrical with respect to the axis line in the X-direction.
Thus, the center of the second projection member 252R is set on the
axis line of the photoreceptor drum 12 in the X-plane by inserting
the second projection member 252R into this groove portion 123Rh,
as illustrated in FIG. 5. That is, the position of the center of
the second projection member 252R in the X-plane is set to coincide
with the axis line position of the photoreceptor drum 12 while the
position in the X-direction of the second projection member 252R is
fixed by the groove portion 123Rh.
Thus, the positions of the center of each of the second projection
members 252F and 252R in the X-plane is set on the axis line of the
photoreceptor drum 12.
Also, the second projection member 252F is supported at two points
in close contact with the side surfaces of the V-shaped portion of
the groove portion 123Fh of the XZ-direction support member 123F.
Thus, the Z-direction position of the LPH 14 is set with high
accuracy at the Z-direction position determined by the position at
which the groove portion 123Fh of the XZ-direction support member
123F is provided.
Additionally, the X-direction position of the second projection
member 252R is fixed by the groove portion 123Rh. The second
projection member 252F is pushed by the press spring 212 toward the
groove portion 123Fh of the XZ-direction support member 123F, that
is, toward the Z-direction. Thus, the X-direction position and the
Z-direction position of the LPH 14 are fixed.
Also, as illustrated in FIG. 6, the second projection members 252F
and 252R and the first projection members 251F and 251R are
disposed on the rod lens array line. Thus, the positions of the
centers of the second projection members 252F and 252R are set on
the axis line of the photoreceptor drum 12 in the X-plane.
Consequently, as illustrated in FIG. 7, the first projection
members 251F and 251R abut against the Y-direction support members
122F and 122R on the axis line of the photoreceptor drum 12 in the
X-plane.
Also, as illustrated in FIG. 5, the first projection members 251F
and 251R are caused to abut against the Y-direction support members
122F and 122R on the axis line of the photoreceptor drum 12. Thus,
the Y-direction position of the LPH 14 is set with high
accuracy.
As described above, the image forming apparatus 1 according to the
present embodiment uses the first projection members 251F and 251R
and the Y-direction support members 122F and 122R, which are
examples of the first positioning means for setting the Y-direction
position of the LPH 14, and the second projection members 252F and
252R and the XZ-direction support members 123F and 123R, which are
examples of the second positioning means for setting the
XZ-direction position of the LPH 14. Thus, the position of the LPH
14 is determined with high accuracy with respect to the axis line
of the photoreceptor drum 12 by separating the functions of such
means from each other.
Further, the first projection members 251F and 251R and the
Y-direction support members 122F and 122R, which are examples of
the first positioning means for setting the Y-direction position of
the LPH 14, are disposed closer to the rod lens array 64 than the
second projection members 252F and 252R and the XZ-direction
support members 123F and 123R, which are examples of the second
positioning means for setting the XZ-direction position of the LPH
14. Consequently, the first projection members 251F and 251R are
caused to abut against the Y-direction support members 122F and
122R at the side of the photoreceptor module MOD (see also FIG. 5),
the first projection members 251F and 251R serve as
supporting-points to suppress the rod lens array 64 from being
bowed by the pushing force of the lifting spring 211 which will be
described later.
Meanwhile, the Y-direction support members 122F and 122R are
disposed coaxially with the rotating shaft 121 of the photoreceptor
drum 12, as illustrated in FIG. 8 which is a cross-sectional view
of the front side portion of the photoreceptor drum 12. The
Y-direction support members 122F and 122R are configured so that
the positions of the surfaces thereof are set at predetermined
positions from the axis line of the photoreceptor drum 12.
More specifically, at both end portions of the photoreceptor drum
12, flanges 124 are fit into the inner circumferential surface
parts of the photoreceptor drum 12 so that the photoreceptor drum
12 and the flanges 124 are integral with one another. The flanges
124 have sintered bearings 125 provided in the inner
circumferential parts thereof. The flanges 124 are axially
supported by the rotating shaft 121 fixed to the photoreceptor
module MOD through the sintered bearings 125. The flanges 124
support the photoreceptor drum 12 rotatably around the rotating
shaft 121. Ball bearings are fit onto the outer circumferential
surfaces of the flanges 124. According to the present embodiment,
the ball bearings, which do not rotate as the photoreceptor drum 12
rotates, are used as the Y-direction support members 122F and 122R
which support the first projection members 251F and 251R at the
side of the LPH 14, so as to prevent reduction in the positioning
accuracy from occurring as the photoreceptor drum 12 rotates. The
Y-direction support members 122F and 122R are supported by bearing
support members 126 provided on the photoreceptor module MOD.
With such a configuration, the photoreceptor drum 12 rotates while
the flanges 124 formed integrally with the photoreceptor drum 12
are axially supported by the rotating shaft 121 fixed to the
photoreceptor module MOD through the sintered bearings, and while
the outer circumferential surfaces of the flanges 124 are axially
supported by the ball bearings serving as the Y-direction support
member 122F that is supported by the photoreceptor module MOD.
Additionally, the apparatus can be manufactured so that the outside
diameter of the rotating shaft 121, the inside diameters and the
outside diameters of the sintered bearings 125, and the flanges 124
are set with good accuracy. Thus, the distance from each of the
positions of the outer ring surface of the ball bearings serving as
the Y-direction support members 122F and 122R to the axis line can
be set with high accuracy. Consequently, the Y-direction position
of the LPH 14 can be set with high accuracy by causing the first
projection members 251F and 251R to abut against the outer ring
surfaces of the Y-direction support members 122F and 122R
constituted by the ball bearings.
Incidentally, the outer ring surfaces of the Y-directions support
members 122F and 122R constituted by the ball bearings are
supported by the bearing support members 126. Thus, the outer ring
surfaces of the Y-directions support members 122F and 122R do not
rotate. Therefore, the first projection members 251F and 251R do
not abrade away. Consequently, the accuracy in the Y-direction
position of the LPH 14 is suppressed from being reduced.
Next, the approaching/separating mechanism (i.e., the retracting
mechanism) for the LPH 14 in the image forming apparatus 1
according to the present embodiment is described below.
As illustrated in FIG. 5, the image forming apparatus 1 according
to the present embodiment has a guide bar 232 disposed by partly
being to the housing 61 of the LPH 14, a slide roll 231 rotatably
supported by the guide bar 232, the lifting springs 211 serving as
the second pushing members adapted to upwardly push the housing 61
of the LPH 14, a retracting member 220 adapted to laterally
slide-move to thereby move the LPH 14 in an up-down direction, a
stage 221 adapted to guide the slide-movement of the slide-movement
of the retracting member 220, the retracting handle 225 adapted to
slide-move the retracting member 220, a guide member 240 adapted to
guide the upward and downward movement of the LPH 14, and a stopper
230 serving as an example of movement limiting means adapted to
limit the movement in the direction to the front side of the LPH
14, as the retracting mechanism.
An operation of the retracting mechanism according to the present
embodiment is described below. FIG. 5 illustrates a state in which
the LPH 14 is set at the exposure position, as described above. The
retracting member 220 slide-moves from the front side to the rear
side by turning the retracting handle 225 clockwise, as viewed in
FIG. 5. FIG. 9 illustrates this state.
When the retracting member 220 is slide-moved from the front side
to the rear side, as illustrated in FIG. 9, the LPH 14 is lifted by
the retracting member 220 is guided by the rail 222 formed on the
side surface of the retracting member 220. The LPH 14 is pushed
down against the pushing forces of the lifting springs 211. At that
time, the LPH 14 is smoothly pushed down while the slide roll 231
rotates on a slope provided on the retracting member 22.
Consequently, the LPH 14 is downwardly separated from the
photoreceptor drum 12.
In this state, the first projection members 251F and 251R and the
second projection members 252F and 252R are separated from the
Y-direction support members 122F and 122R and the XZ-direction
support members 123F and 123R, as illustrated in FIG. 9. At that
time, the first projection members 251F and 251R and the second
projection member 252R are completely detached from the Y-direction
support members 122F and 122R and the XZ-direction support member
123R, respectively. That is, the first projection members 251F and
251R retreat to positions lower than the position of the surface of
the photoreceptor drum 12. The second projection member 252R
retreats to a position lower than the bottom surface of the
XZ-direction support member 123R.
In contrast, the second projection member 252F is not completely
detached from the XZ-direction support member 123F. That is, as
illustrated in FIG. 10 illustrating the relative positions of the
end portion of the second projection member 252F and the
XZ-direction support member 123F, the end portion of the second
projection member 252F is placed in a region to which the
XZ-direction support member 123F is projected from the Y-direction.
The second projection support member 252F retreats to a position
higher than the bottom surface of the XZ-direction support member
123F at lowest.
That is, when the photoreceptor module MOD is attached to and
detached from the apparatus, the first projection members 251F and
251R retreat to positions lower than the position of the surface of
the photoreceptor drum 12. Also, the second projection member 252R
is configured to retreat to a position lower than the bottom
surface of the XZ-direction support member 123R. In contrast, the
groove portion 123Fh of the second projection member 252F is opened
to the rear side. Thus, even in a state in which the second
projection member 252F is disposed at a position higher than the
bottom surface of the XZ-direction support member 123F, the
photoreceptor module MOD can be attached to and detached from the
apparatus.
To set the LPH 14 at the exposure position shown in FIG. 5 again,
the retracting handle 225 is once turned counterclockwise, as
viewed in FIG. 9. Subsequently, the retracting handle 225 is
returned to an original position shown in FIG. 5. Then, the
retracting member 220 slide-moves from the rear side to the front
side. Consequently, the guide bar 232 is guided by the rail 222
formed on a side surface of the retracting member 220.
Consequently, the guide member 232 is pushed up by applying the
pushing force of the lifting spring 211 thereto. At that time, the
guide bar 232 is smoothly pushed up while the slide roll 231
rotates on the slope provided on the retracting member 220.
Consequently, the LPH 14 is upwardly moved and is thus put into
contact with the photoreceptor module MOD.
Then, the LPH 14 is put into contact with the photoreceptor module
MOD. Thus, the first projection members 251F and 251R are caused to
abut against the Y-direction support members 122F and 122R,
respectively. The second projection members 252F and 252R are
supported by the XZ-direction support members 123F and 123R.
In this state, the LPH 14 is pushed by the pushing force of the
lifting spring 211 toward the photoreceptor drum 12. Thus, the
Y-direction of the LPH 14 is fixed. Additionally, the X-direction
and the Z-direction of the LPH 14 are fixed, as described
above.
Meanwhile, as described above, to set the LPH 14 at the Z-direction
position with high accuracy, it is necessary that the second
projection member 252F is supported by being put into close contact
with the side surfaces of the V-shaped part of the groove portion
123Fh at two points. Thus, the LPH 14 is pushed by the pressure
spring 212 fixedly provided to the body frame FRA in the direction
from the rear side toward the second projection member 252F.
However, the LPH14 is pushed by the press spring 212 from the rear
side to the second projection member 252F. Thus, the LPH 14 is
downwardly separated. When the LPH 14 is separated from the
photoreceptor module MOD, the LPH 14 is pushed to the front side
thereof. Consequently, the LPH 14 moves to the front side, and
stops at a position at which the front side end portion of the LPH
14 is in contact with the front side end portion thereof. That is,
in a case where the LPH 14 is downwardly separated, as illustrated
in FIG. 9, the first projection members 251F and 251R and the
second projection members 252F and 252R are placed by being shifted
from positions, at which the Y-direction support members 122F and
122R and the XZ-direction support members 123F and 123R are
disposed, toward the from t side in the Z-direction in the
X-plane.
Therefore, in a case where the LPH 14 is upwardly in contact with
the array and is set at the exposure position, the first projection
members 251F and 251R and the second projection members 252F and
252R are set at the positions of the Y-direction support members
122F and 122R and the XZ-direction support members 123F and 123R,
respectively, from the position shifted in the X-plane.
Thus, to smoothly set the first projection members 251F and 251R
and the second projection members 252F and 252R at the positions of
the Y-direction support members 122F and 122R and the XZ-direction
support members 123F and 123R, respectively, from the position
shifted in the X-plane, the groove portion 123Rh of the
XZ-direction support member 123R supporting the second projection
member 252R has a cross-sectional shape, whose width in the
X-direction is longer than the width in the Z-direction, and is
longer in length in the Z-direction than a shift distance in the
X-plane at the time of operating the retracting handle 225.
However, as described above, the second projection member 252F is
supported at two points on the V-shaped side surfaces of the groove
portion 123Fh of the XZ-direction support member 123F by being in
contact with while is pushed by the press spring 212. Consequently,
the Z-direction position of the LPH 14 is set with high accuracy.
Accordingly, it is impossible to design the groove portion 123Fh of
the Y-direction support member 123F to have a margin of the length
in the Z-direction in the X-plane. Thus, the image forming
apparatus 1 according to the present embodiment is set so that even
when the LPH 14 retreats from the exposure position, an end portion
of the second projection member 252F is placed in a region onto
which the XZ-direction support member 123F is projected from the
Y-direction, and that the second projection member 252F is
retreated to a position higher than the bottom surface of the
XZ-direction support member 123F at lowest.
That is, FIGS. 11A to 11C illustrate the relative positional
relation between the second projection member 252F and the
XZ-direction support member 123F when the LPH 14 is set at the
exposure position from a position at which the LPH 14 is separated
from the photoreceptor module MOD. As illustrated in FIG. 11A, the
top portion of the second projection member 252F is placed higher
than the bottom surface of the XZ-direction support member 123F at
the position, at which the LPH 14 is separated from the
photoreceptor module MOD. That is, the top portion of the second
projection member 252F is placed in the XZ-direction support member
123F. Thus, even in a case where the LPH 14 is shifted to the front
side in the Z-direction in the X-plane, when the LPH 14 is upwardly
moved by the retracting mechanism, the LPH 14 is surely guided in
the groove portion 123Fh of the Y-direction support member 123F. In
such a case, a tapered portion is formed at the top part of the
second projection member 252F and at the lower part of the groove
portion 123Fh of the XZ-direction support member 123FR. Thus, the
second projection member 252F can be more surely and smoothly
guided to the groove portion 123Fn of the XZ-direction support
member 122.
As illustrated in FIG. 11B, the retracting mechanism starts to
upwardly move the LPH 14, and thus, the LPH 14 starts to upwardly
move, the second projection member 252F upwardly moves in the
groove portion 123Fh along the side surface of the groove portion
123Fh of the XZ-direction support member 123F. Then, as illustrated
in FIG. 11C, when the LPH 14 is set at the exposure position, the
second projection member 252F is set at a position at which the
second projection member 252F is supported at two points on and is
in close contact with the V-shaped side surfaces of the groove
portion 123Fh of the XZ-direction support member 123F while pushed
in the direction toward the front side by the press spring 212.
The second projection member 252F is supported at two points on and
is in close contact with the side surfaces of the V-shaped part of
the groove portion 123Fh of the XZ-direction support member 123F.
Thus, as illustrated in FIG. 12 which is a cross-sectional view
illustrating a state in which the second projection member 252F is
supported by the XZ-direction support member 123F, the groove
portion 123Fh is formed so that the opening width M2 of the
V-shaped portion thereof is larger than the outside diameter M1 of
the second projection member 252F. In a case where the opening
width M2 of the V-shaped portion of the groove portion 123Fh is
substantially equal to the outside diameter M1 of the second
projection member 252F, the second projection member 252F is in
contact with the V-shaped side surfaces at four contact points or
is in contact with side surfaces at the front of the V-shaped side
surfaces at two contact points. In this case, the LPH 14 cannot be
set at desirable positions in the Z-direction and in the
X-direction.
Also, the above retracting mechanism according to the present
embodiment is configured so that the width of the guide member 240
is larger than the width of the housing 61 of the LPH 14. FIG. 13A
is a cross-sectional view taken on line L-L shown in FIG. 5. FIG.
13B is a cross-sectional view taken on line N-N shown in FIG. 5. As
illustrated in FIG. 13A, the retracting mechanism is formed so that
the width T2 of the guide member 240 is larger than the width T1 of
the housing 61 of the LPH 14. When an approaching/separating
operation is performed, the degree of freedom in the X-direction of
the LPH 14 increases. Consequently, the second projection member
252F is smoothly supported at two points on the V-shaped portion
side surfaces of the groove portion 123Fh of the XZ-direction
support member 123F, whose lower part is tapered.
Additionally, even in the second projection member 252R, a lower
part of the groove portion 123Rh of the XZ-direction support member
123R, whose width in the X-direction is substantially equal to the
outside diameter of the first projection member 251R, is tapered.
Also, when the LPH 14 is in contact with the array, the LPH 14 has
a degree of freedom of movement in the X-direction. Thus, the
second projection member 252R, whose top part is tapered, is
smoothly supported by the groove portion 123Rh of the XZ-direction
support member 123R.
Incidentally, in the image forming apparatus 1 according to the
present embodiment, the first projection members 251F and 251R are
configured separately from the second projection members 252F and
252R. When the first positioning means and the second positioning
means are configured, the first support member is constituted
separately from the second support member. The first projection
member 251F and the second projection member 252F are formed
integrally with the first projection member 251R and the second
projection member 252R, respectively. Thus, the apparatus may be
configured so that the Y-direction, the X-direction, and the
Z-direction can be set using only one projection portion.
In the foregoing description of the image forming apparatus
according to the present embodiment, this image forming apparatus 1
has been described, which is configured so that the Y-direction
support members 122F and 122R, the XZ-direction support members
123F and 123R are provided at the side of the photoreceptor module
MOD. However, in a case where the Y-direction support members 122F
and 122R, and the XZ-direction support members 123F and 123R can
maintain a predetermined positional relation with the photoreceptor
drum 12, the Y-direction support members 122F and 122R, and the
XZ-direction support members 123F and 123R can be provided at the
side of the body of the image forming apparatus 1.
As described above, in the image forming apparatus according to the
present embodiment, the first projection members 251F and 251R at
the side of the LPH 14 abut against the Y-direction support members
122F and 122R provided at the side photoreceptor module MOD,
respectively. Thus, the position in the Y-direction of the LPH 14
is set. Simultaneously with this, the second projection members
252F and 252R at the side of the LPH 14 are supported by the
XZ-direction support members 123F and 123R provided at the side of
the photoreceptor module MOD, respectively. Consequently, the
position in the X-direction and the position in the Z-direction of
the LPH 14 are simultaneously set. Then, the first projection
members 251F and 251R are disposed closer to the rod lens array 64
than the second projection members 252F and 252R. Consequently, the
image forming apparatus according to the present embodiment can
suppress flexure of the rod lens array 64 caused when the first
projection members 251F and 251R are caused to abut against the
Y-direction support members 122F and 122R at the side of the side
of the photoreceptor module MOD. Also, the positioning of the LPH
14 with respect to the photoreceptor drum 12 can be achieved with
good accuracy.
Thus, a high-quality image with extremely small skew and distortion
can be formed.
The foregoing description of the embodiments of the present
invention has been provided for the purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Obviously, many
modifications and variations will be apparent to practitioners
skilled in the art. The embodiments were chosen and described in
order to best explain the principles of the invention and its
practical applications, thereby enabling others skilled in the art
to understand the invention for various embodiments and with the
various modifications as are suited to the particular use
contemplated. It is intended that the scope of the invention be
defined by the following claims and their equivalents.
* * * * *